5-Aminosalicylic acid in patients with an ileo-rectal anastomosis. A comparison of the fate of sulfasalazine and Pentasa

Prolonged-release mesalazine: a review of its therapeutic potential in ulcerative colitis and Crohn's disease

Prolonged-release mesalazine (Pentasa) consists of ethylcellulose-coated microgranules from which mesalazine (known in the US as mesalamine) is released in the small and large intestine in a diffusion-dependent manner. Dose-dependent improvements in clinical and endoscopic parameters have been reported with prolonged-release mesalazine 2 and 4 g/day in clinical trials in patients with mild to moderately active ulcerative colitis. Induction of clinical and endoscopic remission was achieved in more patients receiving a daily dosage of 4 g/day than in those receiving placebo. In patients with ulcerative colitis in remission, prolonged-release mesalazine is effective in reducing the rate of relapse. Higher dosages tend to be more effective, and a 12-month remission rate of 64% has been reported for patients treated with a 4 g daily dosage of this formulation. Comparative data indicate that prolonged-release mesalazine has similar efficacy in maintaining remission to molar equivalent doses of sulfasalazine. Data from a study in patients with mild to moderately active Crohn's disease indicates that higher dosages (4 g/day) of prolonged-release mesalazine are more effective than placebo in reducing disease activity. After 16 weeks' treatment, 64% of patients receiving a 4 g/day dosage experienced clinical improvement and 43% attained remission. In studies of patients in remission of Crohn's disease, the formulation appears to be more effective in preventing relapse in patients with isolated small bowel disease than in those with colonic involvement. The tolerability profile of oral prolonged-release mesalazine is similar to that of placebo and the incidence of adverse events does not appear to be dose-related. Nausea/vomiting, diarrhoea, abdominal pain and dyspepsia occur most frequently, although their incidence is low. Reports of nephrotoxicity during prolonged-release mesalazine treatment are rare.

CONCLUSIONS

Oral prolonged-release mesalazine is effective for maintenance and induction of remission of mild to moderately active colitis, both in patients with distal disease and in those with pancolitis. The formulation has similar efficacy to that of equimolar concentrations of sulfasalazine. Prolonged-release mesalazine also appears to be effective in the treatment of Crohn's disease, and maintenance therapy is of particular value in patients with isolated small bowel involvement. Evidence suggests that higher dosages (3 to 4 g/day) of prolonged-release mesalazine have additional therapeutic benefits over lower dosages in patients with inflammatory bowel disease without increasing the incidence of adverse events.

Clinical pharmacology in gastroenterology: development of new forms of treatment of inflammatory bowel disease

Kinetic-dynamic aspects of the development of slow-release mesalazine, Pentasa (now an established treatment of inflammatory bowel disease (IBD)), and cyclosporin, a T cell selective immunosuppressant (still in the investigative phase), are reviewed as examples of Danish contributions at an early stage to international, clinical drug research. Apart from increasing the therapeutic options for patients with IBD, current and future studies with these (and other) drugs may add important clues to a more precise understanding of the basic pathogenetic mechanisms (e.g. cytokines, adhesion molecules) involved in these diseases. The future development and clinical implementation of novel drug designs in IBD and other gastrointestinal diseases may be expected to benefit from a continued or even closer collaboration between clinical gastroenterologists and basic research institutions, including the pharmaceutical industry at an early stage.

Bacterial acetylation of 5-aminosalicylic acid in faecal suspensions cultured under aerobic and anaerobic conditions

After oral administration of 5-aminosalicylic acid a substantial proportion of the acetylated form is excreted in the faeces. We have studied the role of the faecal microflora in acetylating 5-aminosalicylic acid. In faeces incubated under both aerobic and anaerobic conditions there was acetylation of 5-aminosalicylic acid. Of the anaerobic bacteria isolated from a 10(8) faecal dilution 44% were able to acetylate 5-aminosalicylic acid. We conclude that the normal faecal microflora contribute to the acetylation of 5-aminosalicylic acid.

Acetylation of 5-aminosalicylate by hamster colon arylamine N-acetyltransferase

Recent evidence suggests that 5-aminosalicylate acts as an anti-inflammatory agent by virtue of its ability to act as a free-radical scavenger. The major metabolite, N-acetyl-5-aminosalicylate is not an effective free-radical scavenger. We have demonstrated that an arylamine N-acetyltransferase from hamster colon can directly acetylate 5-aminosalicylate, suggesting that the colon may have the ability to modulate the activity of this agent through metabolic inactivation.

Mesalazine. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic potential in chronic inflammatory bowel disease

Mesalazine (5-aminosalicylic acid; mesalamine), the active moiety of sulphasalazine (salazosulfapyridine), is available in specially formulated oral and rectal forms for the treatment of active ulcerative colitis of mild to moderate severity and for maintenance therapy during disease remission. Tablets or capsules coated with acrylic-based resin and tablets containing microgranules coated with ethylcellulose deliver mesalazine to the distal small intestine and colon, thus avoiding the need for the carrier, sulphapyridine, which is responsible for many of the adverse effects associated with sulphasalazine. Since mesalazine is released in the small intestine from some coated preparations in contrast to sulphasalazine, these oral formulations have therapeutic potential in Crohn's disease. A limited number of therapeutic trials suggest that orally administered mesalazine 1.5 to 2.4g daily is of similar efficacy to sulphasalazine 2 to 3g daily in patients with mild to moderate ulcerative colitis. The efficacy of mesalazine enemas has been more widely investigated, a dose of 1 to 4g once daily being consistently more effective than placebo and apparently similar to enemas of prednisone 25mg or oral sulphasalazine 3g. Initial results suggest that mesalazine 4g enemas may be more effective than those containing hydrocortisone 100mg. Mesalazine and sulphasalazine in approximately equivalent oral dosages are similarly effective in maintaining remission in ulcerative colitis. Orally administered coated mesalazine is generally well tolerated by about 85% of patients allergic to or intolerant of sulphasalazine, the remainder experiencing similar reactions to both drugs. Adverse effects of mesalazine enemas are confined to local irritation and effects resulting from enema-tip insertion. Thus, orally administered coated mesalazine is a suitable alternative to sulphasalazine in the treatment of patients with mild to moderate active distal ulcerative colitis and for maintaining remission particularly in patients allergic to or intolerant of sulphasalazine. In patients who find enema therapy acceptable, mesalazine enemas are effective and well tolerated.

Effects of mesalazine substitution on salicylazosulfapyridine-induced seminal abnormalities in men with ulcerative colitis

Some semen characteristics of eight male patients with clinically inactive ulcerative colitis were investigated. Semen analysis was carried out twice during salicylazosulfapyridine (SASP) treatment and repeated twice after at least 3 months' treatment with mesalazine. The motility variables all showed significant improvement during mesalazine treatment: the graded motility (p less than 0.05), motility in percentage (p less than 0.01), and the penetration in egg white (p less than 0.05). The semen plasma was analyzed for mesalazine and the metabolite Ac-mesalazine during both regimens. There was no difference in the semen plasma concentration of mesalazine during the two regimens, whereas Ac-mesalazine was significantly higher during mesalazine treatment than during SASP treatment, indicating that other SASP metabolites, most likely sulfapyridine, are the agent causing the abnormal sperm characteristics. We suggest that pure mesalazine preparations are a safer alternative in young men with chronic inflammatory bowel disease.

Newer 5-aminosalicylic acid based drugs in chronic inflammatory bowel disease

Since the discovery that 5-aminosalicylic acid (5-ASA) is the active moiety of sulphasalazine in the treatment of chronic inflammatory bowel disease, several new 5-ASA based drugs have been developed. These consist either of slow- or delayed-release formulations of plain 5-ASA or sulpha-free azo compounds of 5-ASA. The different formulations and compounds have varying bioavailabilities, which makes it possible to use them alternatively in different clinical situations. A review of the literature is given, together with suggestions as to how the new drugs might be used in different clinical situations.